To supplement and improve our understanding of how radiation damages normal and neoplastic cells, studies are being performed in combination with drugs such as actinomycin-D and adriamycin. Since both these agents alone are capable of producing very severe toxic effects, it is important to determine how they interact with radiation so that serious problems that often arise with combined therapy can be avoided. We are, therefore, studying normal tissue (heart and liver) in culture, as well as in whole animals, in order to gain insight into the ways such injry to normal tissue can be modified or damage to malignant tissue enhanced. Such studies will be continued, and it is hoped that they will provide information for a better rationalization in the future of combined chemo-and radiotherapy.